Cellulosic fabric reacted in wet state with ethylene chlorohydrin and thereafter with dimethylol ethyleneurea under dehydrating conditions



United States Patent Int. Cl. D06m 13/54 US. Cl. 8-116.3 1 Claim ABSTRACT OF THE DISCLOSURE Cellulosic fabrics are reacted with a monofunctional reactant and thereafter cross-linked with a polyfunctional reactant to improve the wash-wear properties thereof.

A non-exclusive, irrevocable, royalty-free license in the invention herein described throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

A primary object of the present invention is to provide a process for treating cellulosic fabrics to give improved wash-wear properties. A further object of this invention is to provide a process for treating cellulosic fabrics whereby the fabric is treated with a non-crosslinking agent and a cross-linking agent.

Fabrics composed of cellulosic fibers do not inherently possess smooth drying properties. To impart this property to cellulosic fabrics, it is customary to treat the fabric with an agent and a catalyst to promote a reaction between the agent and cellulose or to promote reaction of the agent itself. These treatments are believed to convert the cellulosic fiber from an assembly of linear molecules to one with -a crosslinked structure. The normal crosslinking reaction occurs at high temperature and on dry fabrics. The fibers are therefore crosslinked in a deswollen state.

The treatments described above are effective to a Significant extent in producing wash-wear properties. Fabrics treated in this manner are smoother and possess less wrinkles after washing. The degree of smoothness, however, will vary with the laundry procedure. Best results are usually obtained when the fabric is washed, spun gently to remove water by centrifugal force, and tumble dried in a stream of hot air. Poorest results are usually obtained when the fabric is washed, spun strongly to remove the water and then dried by hanging on a line with no mechanical source of moving air. The latter conditions provide the severest test of the effectiveness for wash-wear treatments.

A method for improving the wash-wear appearance of cellulosic fabric after spinning and line drying is to apply to the fabric two crosslinking treatments. One treatment uses the procedure previously mentioned, i.e., crosslinking on a dry deswollen fiber. The second treatment involves crosslinking the cellulosic fiber while it is swollen by water or some swelling agent. The second treatment in this procedure can precede the first.

It is believed that the severity of the spinning and linedrying laundering is due to the forcing of fiber elements together by centrifugal force on the wet fiber and the binding of the elements to each other by physical entanglement or by the formation of secondary valence forces between atoms in the fiber elements. This can occur readily because the fiber elements are held near each other by crosslinking of the deswollen fibers. As a result,

3,489,503 Patented Jan. 13, 1970 folds and wrinkles introduced by spinning are locked in to give the fabric a mussed or wrinkled appearance. Tumbling in a mechanical dryer tends to remove the wrinkles by mechanical agitation as the bonds between fiber elements are loosened by moist heat. On line-drying, however, there is not enough mechanical action or heat to remove these bonds and, as a result, most of the wrinkles remain.

When fibers are crosslinked in a swollen state, they can still swell. The fiber elements are thus separated and bonds between them do not form as readily. For this reason, crosslinking in the wet state minimizes wrinkling in washing. However, crosslinking in the dry state is also required to prevent wrinkling in use. These requirements led to the treatment with two crosslinking reactions.

This invention relates to a method whereby a swollen cellulose is treated with a noncrosslinking agent. The introduction of the noncrosslinking substitutent group into the swollen cellulose together with a crosslinking in the dry state will give a wash-wear cellulosic fabric with superior performance even after spinning out wash water and drying by hanging on a line in still air.

The use of a noncrosslinking agent instead of :a crosslinking agent to preserve swelling ability has several advantages. Loss of strength that normally occurs with crosslinking agents are not as severe when a noncrosslinking agent is used. Also reagents needed for a noncrosslinking reaction are less expensive than the difunctional reagents needed for crosslinking reactions.

By the process of this invention, cellulosic fabrics can be treated with a monofunctional agent that reacts with the cellulose while the fibers are at least partially swollen and then with a polyfunctional agent that reacts to crosslink the cellulose while the fibers are dry. The order in which the reagents are applied may be reversed but for best results the crosslinking treatment should be the final one.

The monofunctional agent used in the process of this invention should be capable of reacting while the cellulose is partially swollen and the substitutent introduced should remain stable through the crosslinking reaction. Halogenated alcohol such as ethylene chlorohydrin, propylene chlorohydrin, glycerol chlorohydrin, and the like in which the halogen and the hydroxy groups are on adjacent carbon atoms are among the better of the noncrosslinking agents. They can be applied effectively and easily with alkali. This is done by applying the halohydrin to the cellulosic fabric and then applying sodium hydroxide from an aqueous solution containing a salt to inhibit extraction of the halohydrin. After these applications, the wet fabric is heated and then washed. The reaction of the balohydrin to form a beta-hydroxy-alkyl cellulose ether occurs before the cellulose is deswollen by drying. Indeed, it is doubtful that complete deswelling can occur even at high temperatures in the process of this invention because of the presence of the alkali. Washing the fabric after the reaction is necessary to remove the alkali that would interfere with the subsequent crosslinking reactions. After this step, the fabric cannot be completely deswollen by drying presumably because the substitutent introduced physically prevents the collapse of the fiber.

Other non-crosslinking agents may be employed but in general, they are more difiicult to use. Alkyl halides such as methyl chloride, methyl bromide, ethyl chloride, or ethyl bromide may be used but because of their volatility, special equipment and severe reaction conditions are necessary. Higher molecular weight compounds may also be used but a larger quantity is required to obtain the same molar substitution.

Agents that produce wrinkle-resistant cellulosic fabrics may be used for the crosslinking reaction. These are normally the adducts of formaldehyde with amides. Some common classes of crosslinking agents are the polymethylol derivatives of: urea, cyclic ureas, alkyl carbamates, and substituted alkyl carbamates, melamine, triazines, triazones, and urones. The choice of a crosslinking agent may be governed by properties other than those related to the essential nature of this treatment; for example, chlorine resistance or high durability. The crosslinking agent is applied to the fabric in the usual manner, i.e., by applying from an aqueous solution, drying and curing at a high temperature.

Fabrics that are treated by the two step process of this invention show considerable improvement over fabrics treated by the usual single step method. Wash-wear ratings after a normal washing with spinning to dampness and line-drying are noticeably higher. In addition, washwear ratings after tumble drying are also higher when the process of this invention is used in place of the single step process.

In the following examples, which illustrate this invention, all percentages are by weight. Results reported are by procedures described by the American Association of Textile Chemists and Colorists.

EXAMPLE 1 Cotton printcloth is treated with ethylene chlorohydrin by the following procedure. The fabric is wet with ethylene chlorohydrin and is passed through pad rolls to remove the excess. The fabric is then passed through a solution composed of sodium hydroxide dissolved in water saturated with sodium carbonate and is again padded. Following this, the fabric is heated for 7 minutes at 60 C. and then for 3 minutes at 160 C., rinsed in water, soured in 5% acetic acid to remove all traces of alkali and again rinsed before drying. The dried fabric is then padded with an aqueous solution containing 6% dimethylol ethyleneurea and 0.5 Zinc nitrate hexahydrate, dried by heating for 7 minutes in a stream of air at 60 C., cured by heating for 3 minutes at 160 C., washed and dried.

Another sample of cotton printcloth is treated with dimethylol ethyleneurea and zinc nitrate only, omitting the treatment with ethylene chlorohydrin.

Both of the treated printcloths are subjected to a laundering in a home-type automatic washing machine using the most vigorous procedure recommended for fabrics composed entirely of cotton. The fabrics are allowed to dry by hanging on a line. They are then compared for smooth-drying or wash-wear properties using the rating system of the American Association of Textile Chemists and Colorists. With this method, a rating of 5 is the highest obtainable and a rating of 1 is the poorest.

After comparison the fabrics are washed again by the same procedure except they are dried in a tumble dryer. They are again compared for smooth-drying properties. Results of the comparison are shown in the following table. The numerical values are the averages of values given by several observers. The superiority of the twostep process using both ethylene chlorohydrin and dimethylol ethyleneurea is evident.

WASH-WEAR RATIN G EXAMPLE 2 Cotton printcloth is padded with ethylene chlorohydrin and then padded with sodium hydroxide dissolved in saturated aqueous sodium carbonate solution.

4 The fabric is heated at 50 C. for 30 minutes, rinsed in water, soured in 5% acetic acid, rinsed again and dried. The fabric is then padded with a solution of 6% dimethylol ethyleneurea and 0.5% zinc nitrate hexahydrate, dried for 7 minutes at 60 C., cured for 3 minutes at 160 C., washed, and dried.

For comparison, another sample of the cotton printcloth was treated by the same procedure but the crosslinking agent 1,3-dichloro-2-pr0panol was substituted for the monofunctional ethylene chlorohydrin.

For further comparison, a third sample of the cotton printcloth is treated with dimethylol ethyleneurea and zinc nitrate only. The first step with ethylene chlorohydrin or dichloropropanol is omitted.

All samples of the treated fabrics are washed in a home-type washing machine with spinning to dampness and drying on a line. They are rated for wash-wear properties when dry. They are then washed again but dried in an automatic tumble dryer before rating for wash-wear properties.

Wash-wear ratings that are obtained are given in the following table. Both treatments using the two steps give properties superior to those given by the treatment with the dimethylol ethyleneurea alone. The treatment using monofunctional ethylene chlorohydrin in the first step is equal if not superior to the one using the crosslinking agent dichloropropanol.

WA SII-WEA R RATIN GS Dimethylol ethyleneurea only We claim: 1

1. A process for treating cellulosic fabrics whereby said process consists of:

(a) wetting the fabric with ethylene chlorohydrin,

(b) removing the excess ethylene chlorohydrin by passing the fabric through pad rolls,

(0) wetting the fabric in about a 10% aqueous solution of NaOH saturated with Na CO (d) drying the fabric and subsequently curing the fabric at a temperature of about 160 C.,

(e) washing the cured fabric to remove unreacted reagents,

(f) drying the washed fabric,

(g) padding the dried fabric from step (f) with a solution containing about 6% dimethylol ethyleneurea and about 0.5 zinc nitrate hexahydrate,

(h) drying the fabric and subsequently curing the fabric at a temperature of about 160 C.,

(i) washing the fabric free of excess reagents.

References Cited UNITED STATES PATENTS 3,175,875 3/1965 Gagarine 8-120 3,189,404 6/1965 Takiyaki et a1. 8-116.3 X 3,254,941 6/1966 Krassig et a1. 8-12O X 3,371,983 5/1968 Barber et a1. 8116.3 X

FOREIGN PATENTS 696,282 8/ 1953 Great Britain. 515,855 12/1939 Great Britain.

GEORGE F. LESMES, Primary Examiner I. CANNON, Assistant Examiner US. Cl. X.R. 8 

